Intraoral 3d scanning with automatic charting

ABSTRACT

A method for intraoral imaging generates one or more output imaging signals from an intraoral probe and acquires multimodal image content from intraoral surface locations according to tissue response from the one or more imaging signals and associates spatial coordinates to the acquired multimodal image content. A surface contour of the patient dentition is generated by stitching the acquired multimodal image content and preserving the association of spatial coordinates with the stitched multimodal image content. Tooth outlines for one or more teeth are generated from the generated surface contour and the generated outlines arranged as a dental chart representing a spatial ordering of the one or more teeth and of supporting gum tissue adjacent to the teeth. The dental chart is populated by analyzing the acquired multimodal image content and associating the analysis to positions on the dental chart according to the preserved association of spatial coordinates and is displayed.

TECHNICAL FIELD

The disclosure relates generally to intraoral imaging and, moreparticularly, relates to methods and apparatuses for automaticgeneration of a tooth chart and related content from intraoral scanning.

BACKGROUND

A dental chart is a widely used tool that supports a dental practitionerin planning and tracking patient treatment. Conventionally, the dentalchart is manually annotated by the practitioner and treatment staff andis stored in the patient folder in order to maintain an updated recordof patient status, treatment progress, and diagnostic concerns.

With the recent adaptation of various electronic tools for imaging anddiagnostic support, there is interest in storing and maintaining dentalchart information online to allow ready access for reference and update.Among solutions developed to meet this need is, for example, theSOFTDENT™ software from Carestream Dental LCC. Electronic solutions ofthis type have helped to improve the efficiency of record-keepingfunctions and provide mechanisms for better integration of patientinformation systems and images. Using automated dental charting withsegmentation and automatic tooth identification utilities, the dentalpractitioner can generate, reference, and maintain a dental chart thatrelates more closely to a particular patient's set of teeth, rather thanto standard models. The displayed dental chart can serve as a convenientindex and link to information individually obtained from a number ofdifferent types of imaging and measurement systems.

For some practitioners, the requirement to manually enter notes andmeasurement information relevant to each tooth using a computer keyboardmakes such a system unattractive in practice, in spite of the perceivedbenefits of digital data storage. Thus, there is a need for automatictooth charting methods and apparatus that can both generate anappropriate dental chart for a particular patient from dental images andpopulate the generated chart with information obtained from applyingautomated diagnostics to the tooth image data.

Although some automated tools for generating a dental chart for displayand integrating the dental chart with image content have been developed,there appears to be appreciable room for improvement. For example,although electronic dental charting allows indexing to image contentfrom various radiographic, optical, and ultrasound sources, in practice,the integration of this image content is typically not straightforward.The task of spatial registration of data from various sources can bechallenging with results that can be unsatisfactory and fall short ofthe accuracy needed for diagnosis and tracking. As a relatedcomplication, data from different sources must be temporallysynchronized with other image data in order to provide updatedinformation on patient condition. Because existing solutions mimic the“snapshot” data recording function of manually maintained charts,advantages of stored data and automatic update have not been exploredand it can be difficult to follow treatment progress. Still othershortcomings relate to limitations in data representation.

Thus, it can be appreciated that there is a need for improvement insystems, apparatuses, and methods that automate the dental chartingprocess and, in particular, provide solutions that integrate the dentalchart with multifunctional and/or multimodal intraoral imaging systems.

SUMMARY

Broadly described, the present invention comprises apparatuses, methodsand systems for automating the dental charting process by integratingthe dental chart with multifunctional and/or multimodal intraoralimaging systems. According to one example embodiment, there is provideda method for intraoral imaging comprising: (a) generating one or moreoutput imaging signals from an intraoral probe; (b) acquiring multimodalimage content from each of a plurality of intraoral surface locationsfor a patient's dentition according to tissue response from the one ormore imaging signals and associating spatial coordinates to the acquiredmultimodal image content; (c) generating a surface contour of thepatient dentition by reconstructing and stitching from a data subset ofthe acquired multimodal image content, and preserving the association ofspatial coordinates of the multimodal image content to the stitchedsurface contour; (d) generating tooth outlines for one or more teethfrom the generated surface contour and arranging the generated outlinesas a dental chart representing a spatial ordering of the one or moreteeth and of supporting gum tissue adjacent to the teeth; (e) populatingthe dental chart by analyzing the acquired multimodal image content andindicating analysis results at one or more positions on the dental chartaccording to the preserved association of spatial coordinates; and (f)displaying, communicating, or storing the populated dental chart.

Advantageously, the present invention acquires multimodal image content,automatically associates and preserves spatial coordinates associatedwith the image content, and automatically analyzes the multimodal imagecontent to populate or update a patient dental chart with minimal inputby a dental technician. By automating the dental charting process, thepresent invention substantially lessens the time required for a dentaltechnician to create and/or update a patient dental chart. As anadditional benefit, the accuracy of a patient dental chart may beimproved over manual generation or updating of a patient dental chart.As yet another benefit, substantially more information is integratedinto a patient dental chart, thereby providing a dental practitionerwith more information on a patient's dentition.

Other desirable advantages and benefits inherently achieved by thedisclosed systems, apparatuses, and methods may occur or become apparentto those skilled in the art. The invention is defined by the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of the example embodiments of the invention, as illustratedin the accompanying drawings. The elements of the drawings are notnecessarily to scale relative to each other.

FIG. 1 is a schematic diagram that shows components of an imagingapparatus for multimode image acquisition and automated dental chartgeneration.

FIG. 2 is a schematic diagram showing an alternate example embodimentfor an imaging apparatus for combined OCT (“Optical CoherenceTomography”) scanning and color image acquisition.

FIG. 3 is a schematic diagram showing another alternate exampleembodiment for an imaging apparatus for multimodal image acquisition.

FIG. 4 is a schematic diagram showing yet another alternate exampleembodiment for an imaging apparatus for multimodal image acquisition.

FIGS. 5A and 5B show functional and geometric aspects of OCT imaging.

FIG. 6 shows a combined OCT and color scanning sequence in schematicform.

FIGS. 7A through 7G show various embodiments of a color lightemitter/detector.

FIG. 7H shows an example embodiment in which RGB (“Red Green Blue”)light detection is performed at the OCT spectrometer.

FIG. 8 is a flowchart that shows an example method for combined colorcalibration.

FIG. 9 is a graph that shows spectral ranges for OCT and reflectanceimaging.

FIG. 10A is a schematic diagram that shows an association of acquiredimage content to each scanned x, y, z location in the scanner field ofview.

FIG. 10B is a schematic diagram that shows re-mapping of the acquiredimage content for a set of locations following the stitching transform.

FIG. 11 is a flowchart that shows a method for OCT processing to obtainOCT imaging content along with a surface point cloud extracted from theOCT content according to an example embodiment of the presentdisclosure.

FIGS. 12A-12E show different types of imaging content acquired andgenerated as part of the OCT processing method, using the example of atooth image having a severe cavity.

FIG. 13 is a flowchart that shows a method for generating a dental chartusing multimodal scan image data according to an embodiment of thepresent invention.

FIGS. 14A, 14B, and 14C show various aspects of a dental chart generatedand displayed according to an example embodiment of the presentinvention.

FIG. 14D shows an example of a generated dental chart with a top view ofthe patient's dentition.

FIG. 14E shows an example of a generated dental chart with a perspectiveview of the patient's dentition.

FIG. 15 is a flowchart that shows a method of steps for automating theprocess of dental chart preparation according to an example embodimentof the present disclosure.

FIG. 16 is a schematic diagram that shows an example of highlightingpositioned on a perspective view of a dental chart and showing thecurrent position of a scanner or probe relative to the overall patientdentition for acquiring image content.

FIG. 17 is a schematic diagram that shows example entries of touchscreeninstructions for identifying particular teeth or other features.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

The following is a detailed description of example embodiments withreference being made to the drawings in which the same referencenumerals identify the same apparatus elements or method steps in each ofthe several figures.

Where used in the context of the present disclosure, the terms “first”,“second”, and so on, do not necessarily denote any ordinal, sequential,or priority relation, but are simply used to more clearly distinguishone step, element, or set of steps or elements from another, unlessspecified otherwise.

As used herein, the term “energizable” relates to a device or set ofcomponents that perform an indicated function upon receiving power and,optionally, upon receiving an enabling signal.

In the context of the present disclosure, the terms “viewer”,“operator”, and “user” are considered to be equivalent and refer to theviewing practitioner, technician, or other person who views andmanipulates an image, such as a dental image, on a display monitor. An“operator instruction” or “viewer instruction” is obtained from explicitcommands entered by the viewer, such as by clicking a button on a cameraor by using a computer mouse or by touch screen or keyboard entry.

In the context of the present disclosure, the phrase “in signalcommunication” indicates that two or more devices and/or components arecapable of communicating with each other via signals that travel oversome type of signal path. Signal communication may be wired or wireless.The signals may be communication, power, data, or energy signals. Thesignal paths may include physical, electrical, magnetic,electromagnetic, optical, wired, and/or wireless connections between thefirst device and/or component and second device and/or component. Thesignal paths may also include additional devices and/or componentsbetween the first device and/or component and second device and/orcomponent.

In the context of the present disclosure, the term “optics” is used,generally, to refer to lenses and other refractive, diffractive, andreflective components or apertures used for shaping and orienting alight beam. An individual component of this type is termed an optic.

In the context of the present disclosure, the term “scattered light” isused, generally, to include light that is reflected and backscatteredfrom an object.

The general term “scanner” relates to an optical system that is used forobtaining various types of intraoral images of patient dentition,including support structures. For OCT (optical coherence tomography)imaging, scanner optics project a scanned light beam of broadbandnear-IR (BNIR) light that is directed to the tooth surface through asample arm and is acquired, as scattered light returned in the samplearm, for detecting interference with light from a reference arm used inOCT imaging of a surface. The general term “raster scanner” relates tothe combination of hardware components that scan light toward a sample,as described in more detail subsequently.

In the context of the present disclosure, the general term “camera”refers more particularly to a device that is enabled to acquire areflectance, 2D (“two dimensional”) digital image from reflected visibleor NIR light, such as structured light that is reflected from thesurface of teeth and supporting structures. According to an exampleembodiment of the present disclosure, a camera that operates at video ornear-video rates is used for acquiring images used to generate a 3D(“three dimensional”) contour image of the teeth and supportingintraoral surfaces.

The term “subject” refers to the tooth or other portion of a patientthat is being imaged and, in optical terms, can be considered equivalentto the “object” of the corresponding imaging system.

In the context of the present disclosure, the phrase “broadband lightemitter” refers to a light source that emits a continuous spectrumoutput over a range of wavelengths at any given point of time.Short-coherence or low-coherence, broadband light sources can include,for example, super luminescent diodes, short-pulse lasers, many types ofwhite-light sources, and supercontinuum light sources. Most shortcoherence length sources of these types have a coherence length on theorder of tens of microns or less.

In the context of the present disclosure, two wavelengths can beconsidered to be “near” each other when within no more than +/−10 nmapart.

In the context of the present disclosure, the terms “color light”,“polychromatic light”, and “RGB light” describe visible lightillumination that is provided for reflectance imaging. The color imageof an intraoral surface location can be considered a reflectance imageor color texture image. As is well known in the color imaging arts, acolor combiner, such as a dichroic surface that transmits one spectralband and reflects another spectral band, can be used to combine colorsfor light traveling in one direction along an optical axis and toseparate colors for light traveling along an axis in the oppositedirection. Thus, the general term “combiner” is typically used for a“combiner/separator” device that both combines and separates lightaccording to wavelength and direction along an optical path.

The term “highlighting” for a displayed feature has its conventionalmeaning as is understood to those skilled in the information and imagedisplay arts. In general, highlighting uses some form of localizeddisplay enhancement to attract the visual attention of the viewer.Highlighting a portion of an image, such as an individual organ, bone,or structure, or a path from one chamber to the next, for example, canbe achieved in any of a number of ways, including, but not limited to,annotating, displaying a nearby or overlaying symbol, outlining ortracing, display in a different color or at a markedly differentintensity or gray scale value than other image or information content,blinking or animation of a portion of a display, or display at highersharpness or contrast.

The term “set”, as used herein, refers to a non-empty set, as theconcept of a collection of elements or members of a set is widelyunderstood in elementary mathematics. The term “subset”, unlessotherwise explicitly stated, is used herein to refer to a non-emptyproper subset, that is, to a subset of the larger set, having one ormore members. For a set “S”, a subset may comprise the complete set “S”.A “proper subset” of set “S”, however, is strictly contained in set “S”and excludes at least one member of set “S”.

An example embodiment of the present disclosure obtains multimodal imagecontent from a single intraoral scan. According to an example embodimentof the present disclosure, the multimodal image content that can beobtained from each scanned location on the intraoral surface can includeimage content of two or more imaging modes, wherein the imaging modescan obtain color/polychromatic or monochrome reflectance image content,fluorescence image content, and depth-resolved image content, forexample. Still other image modes can use signal content from differenttypes of sources, including x-ray or ultrasound image content. Imagemodes can be distinguished from each other in terms of the signal thatis provided and the signal that is acquired for obtaining the image.

Image stitching algorithms that form a more complete, composite image byproperly aligning and joining together content from a number of 2Dimages captured from adjacent views provide a data subset of the fullset of acquired image content and wherein members of this data subsetshare adjacent features, are well known to those skilled in the imageprocessing arts.

FIG. 1 is a schematic diagram that shows components of an intraoralimaging apparatus 300 for multimode image acquisition and automateddental chart generation. An intraoral scanner 314 can be energized toacquire multimode image content, generating the different types of lightsignals and other signals needed to obtain image content from intraoralsurfaces. Light signals may, for example, include polychromatic visibleillumination, excitation illumination for fluorescence, or a scansequence of coherent light beams. Other example signal types can includeultrasound and opto-acoustic signals. Operating under multiple imagingmodes, a single scanner 314 in the FIG. 1 apparatus can provide multiplefunctions such as 3D surface contour imaging and depth-resolved imaging.The scanner 314 is in signal communication with a processor 320, such asa computer. Signal communication can be wired, wireless, or may use somecombination of wired and wireless transfer. Processor 320 is in signalcommunication with a memory 324 or with data storage that provideslonger term data retention and archival. A display 326, also in signalcommunication with processor 320, provides the display of the generateddental chart and associated operator interface.

Images obtained from surface contour imaging form a data subset of theacquired multimodal image content obtained from scanner 314. Processingof this data subset through surface contour reconstruction and stitchingprovides the spatial reference for mapping the data content that isacquired in any imaging mode.

Depth-Resolved Imaging Modes

OCT, ultrasound, and opto-acoustic imaging technologies can each providedepth-resolved imaging from a suitably configured intraoral scanner.Each of these depth-resolved imaging modes direct a series ofdepth-probing output imaging signals to the scanned surface location,using generated signal energy that is capable of penetrating beneath thesurface of tissue to provide depth-resolved image content in addition tosurface contour information. Depth-resolved imaging modes such as OCT,ultrasound, and opto-acoustic imaging can obtain imaging data forsurface contour reconstruction as well as provide useful informationrelated to features that lie beneath the surface of the imaged tissue,accurate to some depth, depending on the limitations of the signalenergy that is used. In addition to depth-related information, variousdepth-resolved imaging apparatus and methods can also provide usefuldata on feature density, distribution, and dimension.

Example embodiments of the present disclosure can use depth-resolvedimaging to address the need for enhanced characterization of the teethand other intraoral features. Using the added information obtained fromdepth-resolved images, the methods of such example embodiments adddimension and further utility to the dental chart that is maintained forthe patient, supplementing the standard tooth-by-tooth assessment thatis conventionally obtained by visual examination with data that waspreviously hidden below the surface.

The description that follows focuses on OCT image acquisition, using OCTas an exemplary type of depth-resolved imaging system that can be usedfor enhanced characterization and generation of a dental chart in anautomated manner. It should be appreciated and understood, however, thatsimilar processing and methods can be used for assembling surfacecontent with alternative depth-resolved imaging types such as, forexample, when using ultrasound and optoacoustic imaging.

Advantageously, the depth-resolved image content is acquired using thesame scanner that obtains reflectance and fluorescence images. Bycombining the image acquisition functions in a single intraoral scanner,methods of the present disclosure address problems of spatial andtemporal synchronization that limited the utility, accuracy, andpracticality of previous imaging solutions.

Example embodiments of the present disclosure can utilize resultsacquired from an apparatus that performs depth-resolved imaging such asoptical coherence tomography (OCT) in order to generate a dental chartand to populate the generated dental chart with results from imageanalysis that support recognition of likely conditions for teeth andgums. OCT results can be combined with 3-D surface contour imagingresults and analysis acquired using the same imaging apparatus, obtainedconcurrently and in register with the OCT data.

Subsequent description gives more detailed information on OCT andmultimodal imaging subsystems that can be used to provide dental chartcontent according to an example embodiment of the present disclosure. Itshould be appreciated and understood that the multimodal imagingapparatus, scanner 314 in FIG. 1 , can acquire any of a number of typesof image data, all registered to a shared set of spatial coordinates.

OCT Imaging Subsystem

OCT has been described as a type of “optical ultrasound”, imagingreflected energy from within living tissue to obtain cross-sectionaldata. In an OCT imaging system, light from a wide-bandwidth source, suchas a super luminescent diode (SLD) or other light source, is directed asa depth-probing output signal along two different optical paths: areference arm of known length and a sample arm that illuminates thetissue or other subject under study. Reflected and back-scattered lightfrom the reference and sample arms is then recombined in the OCTapparatus and interference effects are used to determine characteristicsof the surface and near-surface underlying structure of the sample.Interference data can be acquired by rapidly scanning the sampleillumination across the sample. At each of several thousand points, theOCT apparatus obtains an interference profile which can be used toreconstruct an A-scan with an axial depth into the material that is afactor of light source coherence. For most tissue imaging applications,OCT uses broadband illumination sources and can provide image content atdepths of up to a few millimeters (mm).

Initial OCT apparatuses employed a time-domain (TD-OCT) architecture inwhich depth scanning was achieved by rapidly changing the length of thereference arm using, for example, some type of mechanical mechanism,such as a piezoelectric actuator. TD-OCT methods use point-by-pointscanning, requiring that the illumination probe be moved or scanned fromone position to the next during the imaging session. More recent OCTapparatuses can use a Fourier-domain architecture (FD-OCT) thatdiscriminates reflections from different depths according to the opticalfrequencies of the signals they generate. FD-OCT methods simplify oreliminate axial scan requirements by collecting information frommultiple depths simultaneously and offer improved acquisition rate andsignal-to-noise ratio (SNR).

Because of their potential to achieve higher performance at lower cost,FD-OCT systems based on swept-frequency laser sources have attractedsignificant attention for medical applications that require subsurfaceimaging in highly scattering tissues. There are two implementations ofFourier-domain OCT: spectral domain OCT (SD-OCT) and swept-source OCT(SS-OCT).

SD-OCT imaging can be accomplished by illuminating the sample with abroadband illumination source and dispersing the reflected and scatteredlight with a spectrometer onto an array detector such as, for example, aCCD (charge-coupled device) detector. SS-OCT imaging illuminates thesample with a rapid wavelength-tuned laser and collects light reflectedduring a wavelength sweep using only a single photodetector or balancedphotodetector. With both SD-OCT and SS-OCT, a profile of scattered lightreflected from different depths is obtained by operating on the recordedinterference signals using Fourier transforms, such as Fast-Fouriertransforms (FFT), well known to those skilled in the signal analysisarts.

A recent advance for swept-source OCT imaging is the use of a FourierDomain Mode Locking (FDML) laser source. FDML-OCT scanning offerssignificant increases in acquisition speed for OCT sampling, as well asincreased depth resolution over other OCT types.

Example embodiments of the present disclosure can utilize any of thevarious types of OCT scanning methods, including time-domain, spectral,or frequency-domain OCT. Because the speed advantage is of particularinterest, the description that follows is primarily directed to exampleembodiments that employ swept-source OCT, a type of frequency-domain OCTthat is generally advantageous for faster speed and overall scanningthroughput. However, it should be noted that the compressive samplingmethods or other available OCT methods can be used to improve theresponse of time-domain OCT and other types of OCT as well as withSS-OCT. Methods of the present disclosure can also be used where aspectrometer is used for sensing in the OCT system.

According to an example embodiment of the present disclosure, there isprovided a hybrid imaging apparatus that obtains OCT scanned data withaccompanying color texture content for intraoral features, along withfluorescence image content. The image content that is generated isprovided using the same optical probe.

Referring to the schematic diagram of FIG. 2 , an imaging apparatus 100is shown for multimodal image acquisition that combines OCT scanning,reflectance imaging, and fluorescence image acquisition modes, andwherein the image data for each mode shares the same spatialregistration. Having identical spatial registration relates to acquiringimage content, from each mode, with reference to the same sensorposition and orientation and obviates the need for mapping of one typeof image to another.

Imaging apparatus 100 has an intraoral probe 30 that combines the lightpaths for directed and acquired light of different/multiple imagingmodes along a common or shared optical path, shown as an optical axis OAin FIG. 2 and extending outside probe 30. The distinct directed outputand acquired input signals can then be separated and channeled to/fromthe corresponding optical subsystems within probe 30.

For example, in an OCT light path 40, an OCT light source 10 providesillumination for OCT image scanning. Light source 10 can employ a superluminescent diode (SLD) or other source that emits continuous wavelengthbroadband light. Alternately, light source 10 can be some other type ofsuitable light source, such as a swept source that emits light withcontinuously varying spectral content. One advantaged type of sweptsource is a Fourier Domain Mode Locking (FDML) laser having a high sweeprate and suitable wavelength range for depth-resolved imaging.

In the FIG. 2 configuration, the coherent laser light is directedthrough a first fiber coupler FC1 or wavelength division multiplexer WDMto a second fiber coupler FC2. Fiber coupler FC2 splits the light pathinto a reference arm 42 and a sample arm 44. Light in reference arm 42reflects back from a reference mirror 48 This light is coupled backthrough fiber coupler FC2 and goes to OCT signal detector 46. Lightdirected to sample arm 44 is directed to the subject or sample S by ascanner 24. For intraoral imaging, sample “S” is a surface location ofthe patient's mouth, which can include one or more teeth along with gumsand other supporting features. For OCT depth-resolved image acquisition,reflected and scattered light from sample “S” is coupled back throughsample arm 44 to fiber coupler FC2 and is conveyed to OCT signaldetector 46. The light from reference arm 42 interferes with light fromreference arm 44 to provide the OCT scan data for processing andreconstruction.

In a color reflectance imaging path 50, polychromatic or color light isemitted from a color light emitter/detector (CLED) 52 and directedthrough fiber coupler FC1 or WDM to the second fiber coupler FC2.Coupler FC2 acts as a combiner/separator. The polychromatic visiblelight is combined with the OCT sample light and is simultaneouslydirected to sample “S” through an output scanner 24, part of intraoralprobe 30. Returned reflected color light from the surface location, suchas the surface of the tooth or other intraoral feature, is conveyedthrough fiber coupler FC2 back to CLED 52. CLED 52 senses the colorcontent from the reflected light to form a reflectance image of sample“S”. A control logic processor 60 is in signal communication with OCTsignal detector 46, CLED 52, and light source 10 to record and processthe OCT output data from interference and combine this data with thecolor data from the intraoral surface. The resulting combined imagecontent can then be presented on a display 72 and can alternately becommunicated, transmitted, and/or stored.

The reflectance image can be used for a variety of purposes, such as toprovide a high resolution 2D intraoral image for documentation andpatient communication. Its color content (e.g. R, G, and B image values)can also be used for determining the shade of a tooth.

Fluorescence imaging employs components of reflectance imaging path 50,optionally using a separate light source for directing excitationillumination of a suitable wavelength range for stimulating the surfacelocation to generate fluorescent light image content. In this case, along-pass spectral filter can be used in the detector of CLED 52 tosense the fluorescent light signal, forming a fluorescence image ofsample “S”.

The schematic diagrams of FIGS. 3 and 4 show similar imaging apparatuses120 and 140, respectively, having slightly different light patharrangements for combining the OCT and reflectance imaging functions. Inthe FIG. 3 arrangement of imaging apparatus 120, the OCT path can be thesame as that described previously with respect to imaging apparatus 100in FIG. 2 . The light from color light emitter/detector (CLED) 52 isdirected through a fiber coupler FC3 and shares the sample arm with OCTlight. This combined light is directed to the subject or sample “S”through scanner 24. Backscattered color light from the intraoral surfaceis conveyed through fiber coupler FC3 to color light emitter/detector(CLED) 52 to measure the color content, recorded and processed byprocessor 60. The resulting combined image content can then be presentedon a display 72 and can alternately be communicated, transmitted, and/orstored.

In the FIG. 4 configuration of imaging apparatus 140, the OCT path isthe same as that described previously with respect to imaging apparatus100 in FIG. 2 . The light from color light emitter/detector (CLED) 52 isdirected into the sample path through a dichroic combiner 54, that has areflective surface and a dichroic surface in the configuration shown.Backscattered color light from the intraoral surface is conveyed back toCLED 52 through combiner 54 for detection and measurement, recorded andprocessed by processor 60. The resulting combined image content cansimilarly be presented on a display 72 and can alternately becommunicated, transmitted, and/or stored.

According to an example embodiment of the present disclosure, thedifferent signals that are directed from the scanner to an intraoralsurface location share a common axis.

Scanning Method for OCT Imaging

The schematic diagrams of FIGS. 5A and 5B show a scan sequence that canbe used for forming tomographic images using the OCT apparatus of thepresent disclosure in a Fourier domain acquisition. The sequence shownin FIG. 5A shows how a single B-scan image is generated. Raster scanner24 (FIG. 2 ) scans the selected light sequence over the subject, sample“S”, point by point. A periodic drive signal 92, as shown in FIG. 5A, isused to drive the raster scanner 24 galvo mirrors to control a lateralscan or B-scan that extends across each row of the sample, shown asdiscrete points 82 extending in the horizontal direction in FIGS. 5A and5B. At each of a plurality of points 82 along a line or row of theB-scan, an A-scan or depth scan, acquiring data in the z-axis direction,is generated using successive portions of the selected wavelength band.FIG. 5A shows drive signal 92 for generating a straightforward ascendingsequence using raster scanner 24, with corresponding micro-mirroractuations, or other spatial light modulator pixel-by-pixel pixelactuation, through the wavelength band. The retro-scan signal 93, partof drive signal 92, simply restores the scan mirror back to its startingposition for the next line. No OCT data is obtained during retro-scansignal 93.

It should be noted that the B-scan drive signal 92 drives the galvomirror of scanner 24 for raster scanner 90 as shown in FIGS. 2-4 . Ateach incremental position, point 82 along the row of the B-scan, anA-scan is obtained. To acquire the A-scan data, the tuned laser or otherOCT light source sweeps through a spectral sequence controlled by aprogrammable filter in the OCT source 10. Thus, in an example embodimentin which the light source sweeps through a 30 nm range of wavelengths,this sequence is carried out at each point 82 along the B-scan path. AsFIG. 5A shows, the set of A-scan acquisitions executes at each point 82,that is, at each position of the scanner 24. By way of example, therecan be 2,048 measurements for generating the A-scan at each position 82.

FIG. 5A schematically shows the information acquired during each A-scan.An interference signal 88, shown with DC signal content removed, isacquired over the time interval for each point 82, wherein the signal isa function of the time interval required for the spectral sweep, withthe signal that is acquired indicative of the spectral interferencefringes generated by combining the light from reference and feedbackarms of the OCT interferometer components. The Fourier transformgenerates a transform T for each A-scan. One transform signalcorresponding to an A-scan is shown by way of example in FIG. 5A.

From the above description, it can be appreciated that a significantamount of data is acquired over a single B-scan sequence. In order toprocess this data efficiently, a Fast-Fourier Transform (FFT) is used,transforming the time-based signal data to corresponding frequency-baseddata from which image content can more readily be generated.

In Fourier domain OCT, the A-scan corresponds to one line of spectrumacquisition which generates a line of depth (z-axis) resolved OCTsignal. The B-scan data generates a 2D OCT image along the correspondingscanned line.

Raster scanning is used to obtain multiple B-scan data by incrementingthe raster scanner 24 acquisition in the C-scan direction. This isrepresented schematically in FIG. 5B, which shows how 3D volumeinformation is generated using the A-scan, B-scan, and C-scan data.

As noted previously, the wavelength or frequency sweep sequence that isused at each A-scan point 82 can be modified from the ascending ordescending wavelength sequence that is typically used. Arbitrarywavelength sequencing can alternately be used. In the case of arbitrarywavelength selection, which may be useful for some particularimplementations of OCT, only a portion of the available wavelengths areprovided as a result of each sweep. In arbitrary wavelength sequencing,each wavelength can be randomly selected, in arbitrary sequential order,to be used in the OCT system during a single sweep.

Multimodal Imaging Sequence

FIG. 6 shows the combined OCT and color scanning scheme in schematicform. Scanner 24 steers both the color light beam and OCT light beam tosample “S” in a two-dimensional (x, y) raster scan at each point 82,with x∈[0,L−1] indexed along the x scanning axis. The orthogonalcomponent, y∈[0, M−1] is indexed along the y scanning axis. The colorsignal with three reflectance values (R(x, y), G(x, y), B(x, y)) and theOCT signal I_(OCT)(x,y) with dimension “N” (for “N” data points) in thedepth direction are acquired corresponding to each scanned position (x,y).

When the 2D scanner 24 scans continuously, a 2D color image is populatedwith a number L×M of color pixels; correspondingly a 3D OCT volume isreconstructed with values L×M×N. The (R(x, y), G(x, y), B(x, y)) valuesare inherently registered with I_(OCT)(x,y) along lateral directions.FIG. 6 part (b) shows the inherent mapping provided for the colorcontent at each point 82 corresponding to the OCT scan, with values(R(x, y), G(x, y), B(x, y)) mapped to corresponding I_(OCT)(x,y)measurements. FIG. 6 part (c) shows I_(OCT)(x,y,z_(i)) with the surfacepoint intensity at (x,y,z_(i)), wherein z_(i) is depth of surface from azero-delay line along the A-line OCT signal. The color texture (R(x, y),G(x, y), B(x, y)) is thus mapped directly to the OCT signal at (x,y,z₀).

An example embodiment of the present disclosure preserves the spatialmapping of data from different imaging modes, including OCT andreflectance imaging, in the surface reconstruction that is formed. Thedental chart that is generated from the surface reconstruction can thenincorporate data on multiple characteristics of teeth, gums, and otherfeatures without the need for separate alignment processing fromdifferent types of scanning. This arrangement not only allows the dentalchart to be generated without a separate alignment step, but also allowsstraightforward updating of dental chart contents using subsequentscans. Thus, for example, a complete scan can be used for initialgeneration of the dental chart, incorporating reflectance image content,color shade, 3D surface profiles, OCT depth-resolved data, andfluorescence data, and preserving the spatial association of each datatype. Subsequent to this initial scan, a partial scan can be performed,such as scanning an implant site, an individual tooth requiringtreatment, or other partial portion of the dentition. Reconstructedsurfaces of the new scan can be stitched to the 3D surfaces of thedental arch initially generated. Updated information for the scannedportion, including updated data from multiple modes, can then be readilyaligned with the previously scanned content and used to modify theexisting dental chart.

CLED Structure and Functional Components

FIGS. 7A, 7B, and 7C show different example embodiments of color lightemitter/detector CLED 52. Laser diodes LD1, LD2, and LD3 are red, greenand blue laser diodes, respectively. Lenses L1, L2 and L3 are thecorresponding collimation lenses used with each of LD1, LD2, and LD3 togenerate collimated light beams.

In the FIG. 7A arrangement, collimated beams are combined onto the samelight path by dichroic mirrors DM1 and DM2. Mirrors DM1 and DM2 haveappropriate cutoff wavelengths for corresponding routing of light to andfrom the light path, such as center wavelengths of red and green laserdiodes LD1 and LD2. Lens L4 couples the light from the shared path intoa single mode optical fiber 74 to provide full color or polychromaticlight. Full color light that has been backscattered from the sample “S”is coupled back to CLED 52. Each color light is coupled back to itsoriginal channel through beam splitters BS1, BS3, and BS3 and a portionof the light power is directed to corresponding photodiodes PD1, PD2,and PD3 for measurement.

In the FIG. 7B configuration, a trichroic beam splitter TB S withdichroic filters F1 and F2, similar to a Philips prism, combines thelight from Red, Green, and Blue laser diodes LD1, LD2, and LD3 ontooptical fiber 74, coupled through lens L4. Full color light that hasbeen backscattered from the subject, sample “S”, is coupled back to CLED52. Each color light is coupled back to its original channel throughtrichroic beam splitter TBS.

In the FIG. 7C configuration, a wave division multiplexer WDM is usedfor combining and separating the Red, Green, and Blue light from theirrespective color channels.

In the FIG. 7D configuration, a fiber combiner 76 is used for combiningand separating the Red, Green, and Blue light from their respectivecolor channels.

In the FIG. 7E configuration, two fiber combiners 76 are used, one forcombining the outgoing Red, Green, and Blue light onto a single channel,the other for separating the returned Red, Green, and Blue light totheir respective color channels.

In the FIG. 7F configuration, a wide-bandwidth visible light source,such as a supercontinuum laser SCL, serves as the light source for colorimaging. The SCL has a continuous visible spectrum output. Wavelengthdivision multiplexer WDM in the path of returned light separates thebackscattered light and redirects the light to each respectivephotodiode PD1, PD2, PD3. A fiber coupler FC is used to couple the lightto and from fiber 74.

In the FIG. 7G configuration, a pair of wave division multiplexers WDMand variable attenuators VA are used to modulate the SCL light in theemission path. A WDM in the path of returned light separates thebackscattered light and redirects the light to each respectivephotodiode PD1, PD2, PD3. A fiber coupler FC is used to couple the lightto and from fiber 74.

The FIG. 7H configuration shows an example embodiment in which RGB lightdetection is performed at the OCT spectrometer. Input polychromaticlight is coupled to the OCT scanning system, as shown in previous FIGS.7A-7G. Detection of the polychromatic light utilizes a spectralseparator 124, such as a grating or prism to provide spectral separationof the light, directing red, green, and blue light to correspondingdetectors 126 r, 126 g, 126 b at appropriate angles, as determined bygrating, prism, or other separator characteristics.

Light Source Options

Visible light Vis used in the scanner optics can be of multiplewavelengths in the visible light range. The Vis source can be used, forexample, for color-coding of the projected structured light pattern. TheVis source can alternately be used for white light image preview or fortooth shade measurement or color or texture characterization.

Vis light can be provided from a conventional bulb source or mayoriginate in a solid-state emissive device, such as a laser or one ormore light-emitting diodes (LEDs). Individual Red, Green, and Blue LEDsare used to provide the primary color wavelengths for reflectanceimaging.

In addition to providing a structured light pattern, the Vis source canalternately provide light of particular wavelengths or broadband lightthat is scanned over the subject for conventional reflectance imagingsuch as, for example, for detecting tooth shade or for obtaining surfacecontour data by a method that does not employ a light pattern such as,for example, structure-from-motion imaging.

A violet light, in the near-UV region can be used as the excitationlight for tooth fluorescence imaging. Backscattered fluorescence can becollected by the OCT light path. The fluorescence image can be detectedby the same detector path of the Fourier domain OCT, but at a differentlateral spectrum location.

Color Image Processing and Calibration

For system calibration and imaging, the reflectance imaging apparatusshould be calibrated to a reference standard. R, G, B laser emission isadjusted to provide balanced light intensities. Background signals arecaptured with sample “S” removed from the sample arm. The R, G, Bphotodiodes, PD1, PD2, and PD3, respectively, detect background signalsthat are reflected from the components in the light path. Backgroundsignals are subtracted from the R, G, and B signals, respectively. Thecolor image calibration method is similar to that used in colorphotography which is also adapted in the calculation flowchart of FIG. 8.

FIG. 8 shows a color calibration sequence that can be used for the colorscanner that performs both OCT and RGB imaging. RGB signals are obtainedfrom a calibration target, such as a gray or white light referencepatch, in a reference imaging step 700. Values from a standard colormodel such as sRGB of the reference white patch or other calibrationtarget are acquired in a standard color model step 710. A least squarescalculation or other suitable method for obtaining the calibrationtransform between the RGB signals and sRGB is performed at a calibrationstep 720, generating a calibration matrix at a transform step 730. Thecalibration matrix is applied to the RGB signals obtained from areflectance imaging step 732 to generate a calibrated RGB signal 734.This is combined with OCT surface detection obtained in an OCT surfaceimaging step 740. An attachment step 750 then combines the OCT surfacedetection data in register with calibrated RGB data to provide acombined output.

The difference in spectral ranges for the two imaging modes makes thecombination of OCT light and RGB color light possible, either usingspectral division or amplitude division.

FIG. 9 shows the spectrum distribution of visible R, G, B light andinfrared OCT light waves. As can be readily seen from this mapping, thespectral wavelength ranges are non-overlapping. Visible light rangesfrom wavelengths of about 380 nm to about 740 nm. The infrared lightranges from wavelengths above 740 nm to about 1600 nm. FIG. 9 also showsrelated dichroic mirror cut off and bandpass wavelengths for WDMoperation. Additional color content can be added to provide moreaccurate shade matching, such as a violet V wavelength (less than about450 nm), as shown in the spectral diagram of FIG. 9 .

Illumination for fluorescence imaging can be at wavelengths near thevisible blue region, or in the violet or ultraviolet range.

An alternate approach to meeting the need for combined OCT and colortexture image data uses an OCT scanner that is coupled with a colorpreview camera for obtaining the needed image content. When using thisalternate approach, processing is needed in order to register the colortexture data with the OCT scan content.

Preserving the Association of Image Data with Corresponding SurfaceLocation

In each of the FIGS. 2-4 configurations, CLED signal detection and OCTsignal detection can be synchronized and share the same optical path inthe sample arm to and from the sample probe 30 and its scanner 24.

With high-rate image acquisition for different modes, a substantialamount of image content can be obtained in a single scan using imagingapparatus 100. Instead of requiring some type of manual “mode-switching”or requiring a change in scanning practices, imaging apparatus 100 canbe configured for multimode operation so that each scan of the patient'smouth can acquire image content in multiple modes. With thisarrangement, the different types of image content obtained in each scancan be integrated in surface reconstruction, stitching, and display ofthe complete dental arch. Data that identifies each imaged surfacelocation, typically identified using Cartesian x, y, z coordinates, canbe spatially associated with each type of image data that is acquired atthat surface location.

Referring to the schematic diagram of FIG. 10A, an association ofacquired image content to each scanned x, y, z spatial location in thescanner 314 field of view is shown. Repeated execution of the imagingacquisition sequence during the scan, 3D surface reconstruction, andstitching generates an association between the acquired image contentand the calculated x, y, z location coordinates. This spatialassociation can be formed, stored, and represented in various ways. TheFIG. 10A example shows generating a set of association vectors 510corresponding to each scanned location of the patient dentition. Thevector 510 data structure is merely one example mechanism forrepresenting the association obtained between the spatial location (x,y, z) and the data acquired at that location.

According to an example embodiment of the present disclosure, preservingthe association of spatial coordinates with the results of tissueresponse to a signal follows a similar sequence for each imaging mode.Working backward from the reconstruction and stitching, control logiccan relate one image frame to each surface point such as by using theimage frame orthogonal to a vector that is orthogonal to the surfacepoint. The data value corresponding to a particular point in the framecan be the most accurate measure of tissue response at a correspondingpoint on the surface. Data related to a point in the stitched surfacecan alternately be averaged such as taking a weighted average of allpoints used for stitching at the location.

Preserving the association of spatial coordinates with the results oftissue response to light or other stimulus at each intraoral locationsimplifies the problem of matching and mapping the different types ofdata obtained to an automatically generated dental chart. Instead ofrequiring computationally intensive methods for feature detection andalignment of separate data content, the preserved association allows the3D surface reconstruction and stitching operation to serve as areference for organizing and displaying the information obtained frommultiple imaging modes.

In order to preserve the association of the multimodal image contentwith its spatial coordinates, the stitching algorithm that is used cantransform image coordinates and link the corresponding content to thenew coordinates in the transformation. The schematic diagram of FIG. 10Bshows re-mapping of the acquired image content for a set of locationsfollowing the stitching transform. Acquired association vectors 510provide structure to the measured data for tissue response for locationsshown with corresponding spatial coordinates (x₁, y₁, z₁), (x₂, y₂, z₂),and (x₃, y₃, z₃). Following the stitching process, these initialcoordinates are transformed to coordinates of the stitched reconstructed3D surface, represented in this example as spatial coordinates (x_(1b),y_(1b), z_(1b)), (x_(2b), y_(2b), z_(2b)), and (x_(3b), y_(3b), z_(3b)).The stitching transformation thus brings along with it the correspondingdata, maintaining the original correspondence between the multimodalmeasurements acquired at each particular intraoral location andcoordinates assigned to a reconstruction from the acquired images. Inthis way, the 3D surface reconstruction and stitching maintain theregistration of different elements of multimodal data to each other,simplifying analysis and presentation of the multimodal image content.

Processing for OCT Imaging

The flowchart of FIG. 11 shows a method for OCT processing to obtain OCTimaging content along with a surface point cloud extracted from the OCTcontent according to an example embodiment of the present disclosure.The raw 2D spectral data 150 with numerous A-scans per each B-scan isprovided over the range of wavelength λ of the light signal, provided as“N” lines with “M” pixels per line. A mapping 152 then provides awave-number value “k” for each corresponding wavelength λ. A backgroundsubtraction 154 executes, calculated along the B direction for each kvalue, and a line of background signal is obtained. Backgroundsubtraction 154, performed on each A-line, helps to remove fixed patternnoise. In a zero-padding operation 156 and a phase correction process160, spectrum sampling is corrected and dispersion-induced OCT signalbroadening obtained. An FFT processing step 162 provides processing andscaling of the phase-corrected data to provide input for a 3D volumerendering and 2D cross-section frame display rendering 166, useful forvisualization and diagnostic support. At the conclusion of step 162, theOCT image content is available.

Subsequent processing in the FIG. 11 method then extracts the pointcloud for surface characterization and subsequent matching/stitching. Asegmentation step 170 is executed to extract the surface contour datafrom the OCT volume data. Object surface point cloud generation step 172provides the surface point clouds of the measured object. Point cloudscan then be used for mesh rendering step 174 along with furtherprocessing. Geometric distortion calibration of OCT images can beexecuted in order to help correct shape distortion. Unless properlycorrected, distortion can result from the scanning pattern or from theoptical arrangement that is used. Distortion processing can use spatialcalibration data obtained by using a calibration target of a givengeometry. Scanning of the target and obtaining the scanned dataestablishes a basis for adjusting the registration of scanned data to 3Dspace, compensating for errors in the scanning system. The calibrationtarget can be a 2D target imaged at one or more positions or a 3Dtarget.

Segmentation step 170, object surface point cloud generation step 172and mesh generation and rendering step 174 of the FIG. 11 method obtainsurface contour data from OCT volume measurements. Importantly, resultsof these steps are the reconstructed surfaces of the object measured byOCT. When reflectance image data and fluorescence image data are alsocaptured during scanning, the OCT volume, reconstructed 3D surface, 2Dreflectance images, and 2D/3D fluorescence images are all linkedtogether, registered to each other, being identified to the same view ofsample “S”.

The generated 3D surface is stitched together to new 3D surfacesreconstructed from scanned data obtained in new views, using matchingmethods commonly known in the art, such as iterative closest point (ICP)merging. The stitching process also makes use of the spatial calibrationdata described above. Successful stitching determines the spatialcoordinates of each point on the imaged surfaces and thus obtains thecorrect spatial relationship between different 3D surfaces. In this way,association of spatial locations of the various types of obtained dataare preserved. OCT and the multimodal image data content obtained by thescanner can thus be automatically registered, without requiringadditional steps.

The 3D surface data, OCT depth-resolved volume, 2D reflectance images,and 2D/3D fluorescence images can be displayed, stored, or transmittedto another computer or storage device. According to an exampleembodiment of the present disclosure, these multimodal image data can beused to form and to populate a dental chart, as described in more detailsubsequently. Processed results of the FIG. 11 method can be directed tosubsequent control logic processing for image and diagnostic analysisfor generation of information needed for arranging the dental chart.

Depending on applications and imaging conditions, various imagesegmentation algorithms can be used in segmentation step 170 of the FIG.11 method to extract object surfaces. Image segmentation algorithms suchas simple direct threshold, active contour level set, watershed,supervised and unsupervised image segmentation, neural network-basedimage segmentation, spectral embedding and max-flow/min-cut graph-basedimage segmentation are well known in the image processing fields and canbe utilized. They can be applied to the entire reconstructed 3D volumeor separately to each 2D frame of the OCT data.

FIGS. 12A-12E show different types of imaging content acquired andgenerated as part of the OCT processing method, using the example of atooth image having a severe cavity. FIG. 12A shows a 2D slice thatcorresponds to a B-scan for OCT imaging. FIG. 12B shows a depth-encodedcolor projection of the tooth with an optional color bar 180 as areference. FIG. 12C shows a corresponding slice of the volume renderingobtained from the OCT imaging content. FIG. 12D shows the results ofsegmentation processing of FIG. 12A in which points along the toothsurface are extracted. FIG. 12E shows a surface point cloud 64 of thetooth generated from the OCT volume data. The surface point cloud 64 canbe obtained from the OCT volume data following segmentation, as shownpreviously with respect to the method of FIG. 11 .

Mapping and Analysis of the OCT Data

As shown in the example images of FIGS. 12A-12E, the depth-resolved OCTdata that is acquired also supports reconstruction of the surfacecontour of teeth, gums, and other features of patient dentition andsupporting structures. In addition, the depth-resolved data itself isassociated or mapped to the reconstructed surface contour. Associationof the depth-resolved data with spatial locations on the surface alsoallows the resulting dental charts that are generated to be spatiallyassociated with analysis or assessment of cavities and other lesions,assessment of the integrity of temporary and permanent fillings,assessment of various prosthetic devices, hardware, and implants. Thisassociation can also help to provide indicators of the health ofspecific areas of the gums and other supporting and nearby tissue.

Surface Contour Imaging using Reflected Light

Unlike OCT imaging described previously, conventional surface contourimaging uses reflectance imaging and provides data for characterizing asurface, such as surface structure, curvature, and contourcharacteristics, but does not provide information on material that liesbelow the surface. Contour imaging data or surface contour image datacan be obtained from a structured light imaging apparatus or from animaging apparatus that obtains structure information related to asurface from a sequence of 2D reflectance images obtained using visiblelight illumination, generally in the wavelength range above about 380 nmand less than a 740 nm threshold, near-infrared light near and extendinghigher than 740 nm, or ultraviolet light wavelengths below 380 nm.Alternate techniques for contour imaging include structured lightimaging as well as other known techniques for characterizing surfacestructure such as, for example, feature tracking by triangulation,structure-from-motion photogrammetry, time-of-flight imaging,interferometric-based imaging, and depth-from-focus imaging. Contourimage content can alternately be extracted from volume image contentsuch as, for example, from the OCT volume content (as describedpreviously with respect to FIG. 11 ) by identifying and collecting onlythose voxels that represent surface tissue.

The phrase “patterned light” is used to indicate light that has apredetermined spatial pattern, such that the light has one or morefeatures such as one or more discernable parallel lines, curves, a gridor checkerboard pattern, or other features having areas of lightseparated by areas without illumination. In the context of the presentdisclosure, the phrases “patterned light” and “structured light” areconsidered to be equivalent, both used to identify the light that isprojected onto the subject in order to derive contour image data.

In structured light imaging, a pattern of lines or other structuredpattern is projected from the imaging apparatus toward the surface of anobject from a given angle. The projected pattern from the surface isthen viewed from another angle as a contour image, taking advantage oftriangulation in order to analyze surface information based on theappearance of contour lines. Phase shifting, in which the projectedpattern is incrementally shifted spatially for obtaining additionalmeasurements at the new locations, is typically applied as part ofstructured light imaging, used in order to complete the contour mappingof the surface and to increase overall resolution in the contour image.

Multimodal imaging devices of the present invention may includedepth-resolved imaging or conventional surface contour imaging. Forexample, the TRIOS® dental intraoral scanner from 3Shape, Copenhagen,Denmark performs surface contour imaging using depth-from-focustechnique and captures color reflectance images and tooth shades duringscanning. The CEREC™ Omnicam™ system from Dentsply Sirona, Salzburg,Austria performs surface contour imaging using structured lighttriangulation technique and captures color reflectance images and toothshades during scanning. International Patent Application No. US2014/070719 entitled “Intra-Oral 3-D Fluorescence Imaging” by Inglese etal. captures 3D surface contours using structured light triangulation,color reflectance images, and 2D/3D fluorescence images.

3D Arch Surface Reconstruction

Reconstruction of the 3D mesh corresponding to a full arch is typicallydone by acquiring a series of slightly overlapping intraoral 3D surfaceviews and stitching them together. The process of identifying over whichportion of the mesh under construction the newly acquired view overlapsis referred to as “matching” or “stitching”. Employing matching methodsfamiliar to those in the surface contour imaging arts, an intraoral 3Dscanner can generate a 3D mesh of an entire arch of a patient as theseparate views are acquired.

As was described previously with reference to FIG. 11 , multiple OCTmeasurements can alternately be used for 3D surface reconstruction,following the same stitching process described above. The OCT data fromsuccessive scans is processed to identify surface content. With respectto the description related to FIGS. 5A and 5B, the surface features arereadily provided by identifying the outermost A-scan data for each B-and C-scan position.

Generating and Populating the Dental Chart

According to an example embodiment of the present disclosure, the imagecontent from any of the available imaging modes can be spatiallyassociated with the surface reconstruction that is generated following ascan. For any of the image data obtained in a scan, spatial locationsare automatically determined as a result of successful stitching. Thesurface reconstruction that is generated preserves the association ofspatial coordinates with the image data that shows the response oftissue in the various modes. Thus, for example, a given coordinate ofthe surface reconstruction can be associated with a particularreflectance imaging value such as an R, G, B value, with a shade, with afluorescence value, and with OCT depth imaging content. Combinedinformation for multiple imaging modes can thus be associated withcoordinate space without the need for separate calibration, alignment,or matching logic.

For example, the reflectance image content and OCT scan content for aparticular intraoral surface location can be associated with a locationon the 3D arch surface reconstruction. This reconstruction can then beused for forming and populating a dental chart, preserving the spatialcoordinate information related to each corresponding area of the dentalchart.

The flowchart of FIG. 13 shows a method for generating a dental chartaccording to scanned data from a scanner device capable of capturingmultimodal image content, such as reflectance imaging, OCT scanning, andfluorescence imaging. A scanning step S1920 acquires 3D contour data andother multimodal image data content. A reconstruction and stitching stepS1930 then reconstructs a 3D surface contour using a subset of thescanned data. As part of step S1930, the reconstruction and stitchingoperation obtains the spatial coordinate information related to imagecontent from multimodal imaging.

Continuing with the FIG. 13 method, a segmentation step S1940 thenperforms tooth segmentation and labeling, based on spatial relationshipsof the surface points obtained in step S1930 and using utilities andapproaches familiar to those skilled in the image reconstruction arts.An outline generation step S1950 generates outline data suitable fordental chart construction such as, for example, providing line art forside and top views. An analysis step S1960 then analyzes the scan datafor the teeth and associated gum structures and associates the analysiswith elements of the dental chart. A display step S1970 presents thegenerated dental chart for viewing on a display and, alternately, storesthe chart for future reference or for transmitting or communicating toanother computing device or data storage unit.

The generated chart can be updated using subsequent scan data from thesame multimodal scanner device. Because the internal spatial referenceof the scanner is unchanged, the reconstructed 3D surface from the newlyscanned data can be stitched to the existing dentition, therebyestablishing spatial locations of the new multimodal image data. Theexisting and updated analysis results at any part of the tooth can beeasily compared to bring attention to changing conditions such as, forexample, presence of fillings (e.g., amalgam, composite) or prosthesis(e.g., crown, bridge, veneer, denture), absence of tooth, onset ofcaries, development of cracks, recession of gum line, and erosion ofenamel.

Because it acquires some amount of depth data, depth-resolved imagingdata (such as, for example, OCT scan data or alternately ultrasound orphotoacoustic data) includes information that can be used for analysisof the condition of teeth and gums. Ultrasound images are useful fordetecting periodontal pocket depths. The reflectance image content canprovide accurate information on tooth contour and overall geometry, aswell as detailed surface features for teeth, gums, and other structures.Fluorescence image content is useful for detecting caries,mineralization state, plaque, and prosthetic materials on the tooth.Each type of information can be used to populate the dental chart thatis generated, allowing ready reference to detailed data about specificfeatures of patient dentition.

Presentation of detailed information can take various forms. Accordingto an example embodiment of the present disclosure, various types ofinformation can be selectively enabled or hidden from view as desired bythe practitioner. This can help to reduce confusion, while stillallowing association and storage of significant information accessiblefrom the dental chart. A layered model can be adapted so that morespecialized information of a particular type is presented as an“overlay”. Thus, for example, information on gum condition can beseparately enabled from information on teeth such as cavities, fillings,implants, or other features.

In addition to generating dental charts in standard view formats, anexample embodiment of the present disclosure can provide some degree ofmanipulation of standard views, for example, allowing perspective views.Cross-sectional views (for example, corresponding to OCT B-scans asdescribed previously) can be viewed at locations of interest. Aprogressive sequence of views can alternately be presented so that theview angle is adjusted based on cursor position. Coordinate locationscan also be displayed for various features, allowing the conventional“flattened”, 2-D dental chart to include annotation that is descriptiveof the actual position of a tooth or other feature.

FIGS. 14A, 14B, and 14C show various aspects of a dental chart generatedand displayed according to an example embodiment of the presentinvention. In FIG. 14A, a displayed dental chart 270 is shown.Individual entries in dental chart 270 can be linked to surface contourimages 276, shown in low-resolution or thumbnail form in FIG. 14A.Coordinate references 272 obtained as part of the scan can be providedon the display. Features such as hovering using a mouse or other pointercan provide both coordinate reference data and any associated imagecontent that relates to an indicated location.

By way of example, FIG. 14B shows an enlarged area E1 of the dentalchart 270, schematically showing a few teeth 120. Related informationfor one of the teeth 120 includes an area of suspected caries 122. FIG.14C includes additional information, highlighting a nearby portion ofthe gum tissue 124 that may be bleeding or show other conditions.Display for various detected conditions of teeth and gums can beseparately enabled or disabled, as described previously, allowing thepractitioner to focus on particular conditions of interest or concern.

FIG. 14D shows an example of a generated dental chart 270 with a topview of the patient's dentition.

FIG. 14E shows an example of a generated dental chart 270 with aperspective view of the patient's dentition. As shown in FIGS. 14D and14E, a reference origin “R” can be displayed, providing a referencedatum for the spatial coordinate associations that are preserved in thereconstruction. A number of thumbnail images 280 can be provided to showthe various types of information available for a selected tooth or gumarea.

According to an example embodiment of the present disclosure, thegraphical arrangement of dental chart data that has been automaticallygenerated can be displayed in a standard dental chart format familiar tothe practitioner or in a 3D format or other format using tooth outlinegenerated according to the procedures described above. A toggle or othercommand can be provided in order to select the display format preferredby the practitioner according to an entered operator instruction.Display format options can include the flat, 2D alignment of thetraditional dental chart as shown in the example of FIG. 14A, the flat2D plan view or top view from a standard chart or from the patient imageas shown in the FIG. 14D example, or the perspective 3D view of theupper or lower jaw as shown in FIG. 14E. Pan, zoom and 3D rotation forindividual teeth, for sets of teeth, or for the jaw structure can bedisplayed using various dental chart representations shown in theexamples of FIGS. 14A-14E. The position of origin “R” can be adjusted,with corresponding changes made to other coordinates of the populateddental chart.

Various dental chart arrangements can be displayed. For example, theconventional dental chart arrangement shown in FIGS. 14A-14C can be mostpreferred by experienced practitioners, who may find this configurationmost readily usable and can take advantage of added features that allowviewing different types of information available from the populateddental chart. The alternative views of FIGS. 14D and 14E can be valuablefor viewing specific information about the spatial arrangement of theteeth and may be more useful in assessing how the teeth are disposedwith respect to each other within the jaw. Annotation can be providedfor different dental chart embodiments, allowing the practitioner andstaff, for example, to record various data during examination orcleaning. FIG. 14D shows an arrangement of annotations 282 that can bedisplayed showing, for example, practitioner observations or showingdetails detected in an automated analysis of tooth condition. Labeling,such as with a tooth number, can be provided and can track toothposition, following the displayed content such as when a 3D view of thedentition is rotated or during zoom or pan operations.

The flowchart of FIG. 15 shows a method including steps that can beexecuted for automating the process of dental chart preparation usingacquired multimodal image data according to an example embodiment of thepresent disclosure. Multimodal image content is obtained in anacquisition step S1510. The multimodal image content can be acquired byusing a single imaging signal, such as a visible light source that hasthe spectral bandwidth to provide both reflectance imaging content andfluorescence. Spatial coordinates are retained with the imageacquisition and provide a mechanism for automatic association of imagecontent originating from multiple imaging modes. Alternately,acquisition step S1510 can use multiple output imaging signals such asemploying light signals of different bandwidths acquired simultaneouslyor in close sequence, directed along a common axis. In a surface contourgeneration step S1520, control logic in the intraoral probe generates asurface contour using the acquired multimodal image content. Stitchinglogic is used to join adjacent images, again preserving the associationof spatial coordinates for the multimodal image content. A tooth outlinegeneration step S1530 then executes and in which probe logic cangenerate tooth outlines for use in the dental chart. Dental chart setupstep S1540 can then assemble the dental chart using the sequence oftooth outlines obtained in step S1530 to show a spatial ordering ofteeth as well as supporting gum tissue adjacent to the teeth. Eachassembled element of the dental chart can then be associated withcorresponding multimodal image content in a dental chart population stepS1550. Step S1550 analyzes the multimodal image content and associatesresults of this analysis with positions and features of the assembleddental chart. A display step S1560 then renders the dental chart to adisplay, as well as generating any necessary data file for storage,transmission, or communication of the populated dental chart to othersystems.

In addition to image content acquired using an intraoral imaging device,example embodiments of the present disclosure can also use, asmultimodal image content, image data obtained from extraoral imagingapparatus such as bite-wing and periapical dental x-ray or cone beamcomputed tomography (CBCT) systems. Imaging modes using radiation can beassociated with spatial coordinates for the intraoral image contentusing various utilities for feature recognition. For example, the volumeimage obtained using CBCT processing can be registered to the surfacecontour or surface mesh obtained by the intraoral imaging apparatususing volume image registration methods commonly known in the art. X-rayand CBCT image content can thus be correlated to the dental chart forready reference and display.

Advantageously, spatial correlation of image content from multipleimaging modes can be readily achieved using an example embodiment of thepresent disclosure. No processing delay is needed for separateregistration processing for image content that is obtained from thescanner 314 (FIG. 1 ). Coordinates of the surface reconstruction can beassociated with a particular reflectance imaging value such as with anR, G, B value, with a shade, with a fluorescence value, and with OCTdepth imaging content, as well as with x-ray and CBCT image content.Combined information for multiple imaging modes can thus inventively beassociated with intraoral coordinate space without the need for separatecalibration, alignment, or matching logic and the processing overheadrequired to achieve registration for image data of different typesrelated to patient dentition.

Update Utilities and Workflow

The capability for straightforward spatial association of image data ofdifferent modes provides a number of options and features useful forimproving the update process. As noted previously, it can be helpful toimage a single tooth or a small portion of the jaw during treatment suchas periodically during various stages of implant preparation or in orderto track ongoing progress of a suspected caries condition, using thesame or another calibrated multimodal intraoral scanner. Exampleembodiments of the present disclosure support update in a number ofways, including the following:

-   -   (i) Dental chart generation and update options. As one option,        the practitioner can choose to generate a new dental chart, such        as with a full scan of intraoral surfaces and a repetition of        the chart generation processing described hereinabove. By        default, the previously acquired dental chart and associated        image content can be stored or archived to maintain historical        data for the patient when the new chart is generated.        Alternately, the practitioner can opt to update the existing        chart with new information specific to one or more teeth or        intervening tissue areas or with new image content relative to        specific imaging modes. This type of partial update requires        that the new surface reconstruction be stitched to the surfaces        of the existing dentition, thereby allowing the new content that        is associated with the new surface reconstruction be mapped to        coordinates of the existing dental chart. Techniques to support        stitching of the newly reconstructed surface to the existing        reconstructed surface are familiar to those skilled in the        imaging arts. The dental chart update option can be fully        automated or may benefit from some measure of operator input,        such as a touch screen, mouse, or keyboard entry that coarsely        identifies the tooth location being probed and scanned by the        operator.    -   (ii) Localized highlighting relative to the update position        and/or content. As noted previously, the practitioner can have        the capability to select a display format for the dental chart,        such as showing the conventional 2D array view (FIGS. 14A-C), a        plan view or top schematic view (FIG. 14D), or a perspective 3D        view (FIG. 14E). To support update scanning operation with the        intraoral probe or scanner 314 (FIG. 1 ), any of a number of        highlighting schemes can be selected. FIG. 16 shows highlighting        330 positioned on a perspective view of the dental chart and        showing the current position of scanner 314, relative to the        overall patient dentition, for the newly acquired image content.        This type of visual operator feedback can be helpful to the        practitioner or technician for assurance that the proper area        for update is being imaged. Other types of highlighting can help        to indicate various imaging modes for which data is acquired.        Color-coding can be used to indicate which type of image content        is available or is currently being updated such as, for example,        orange for OCT image content and green for fluorescent content.        Color or other highlighting method can also be used to indicate        processing status. Boundary coordinates for relating the scanned        area to the overall dental chart and origin “R” can also be        displayed if useful to the technician or practitioner.    -   (iii) Chart-guided update. According to an example embodiment,        markup utilities are provided for identifying areas needing        image content update by entries made on the dental chart. Using        this scheme, the electronically generated, populated dental        chart can be a useful tool for improved communication and for        advancing workflow for the dental treatment team. For example, a        practitioner may want updated image content for teeth numbers        8-11 and for gum tissue between teeth numbers 2 and 5. The        practitioner can electronically mark the dental chart by        entering operator instructions such as by using a mouse or        touchscreen entry. The schematic diagram of FIG. 17 shows        example entries of touchscreen instructions that identify        particular teeth or other features such as by using simple        outlining as shown. A popup menu 290 can provide selections that        allow the practitioner to specify imaging modes for scan        information to be acquired. Using the same or another calibrated        multimodal intraoral scanner, the update process can be carried        out without other detailed positioning sequence. The technician        can operate the probe or scanner 314, scanning over the teeth of        interest and can receive on-screen or audible operator feedback        indicating that some or all requested information from the        practitioner entries has been obtained and updated. This        sequence simplifies the acquisition and processing of        information without requiring written or verbal instructions and        consequent risk of confusion.    -   (iv) Time-lapse display using stored “historical” content for        one or more modes. As part of the update process, previously        stored image content of one or more imaging modes can be        retained for future analysis and presentation. Thus, for        example, progression of a caries condition at one or more teeth        over time can be readily observed and displayed in fluorescence        2D images or OCT cross-sectional (B-scan) images, with the        successively stored image content in registration and rendered        to the display in time sequence, following the familiar model of        a time-lapse video. Time information related to each stored        image can also be displayed as an aid to tracking progress and        rate for a condition. A selection button or other instruction        entry tool on the populated dental chart enables selection and        “playback” of previously stored views and includes the        capability for specifying the particular modes of image content        that display.

The invention has been described in detail with particular reference topresently understood example embodiments, but it should be appreciatedand understood that variations and modifications can be affected withinthe spirit and scope of the invention.

For example, control logic processor 340 can be any of a number of typesof logic processing device including, without limitation, a computer orcomputer workstation, a dedicated host processor, a microprocessor, adigital signal processor, logic array, or other device that executesstored program logic instructions.

The presently disclosed example embodiments are, therefore, consideredin all respects to be illustrative and not restrictive. The scope of theinvention is indicated by the appended claims, and all changes that comewithin the meaning and range of equivalents thereof are intended to beembraced therein.

Consistent with at least one example embodiment, examplemethods/apparatus can use a computer program with stored instructionsthat operate on image data that is accessed from an electronic memory.As can be appreciated by those skilled in the image processing arts, acomputer program of an example embodiment herein can be utilized by asuitable, general-purpose computer system such as a personal computer orworkstation. However, many other types of computer systems can be usedto execute the computer program of described example embodimentsincluding, for example, an arrangement of one or networked processors.

A computer program for performing methods of certain example embodimentsdescribed herein may be stored in a computer readable storage medium.This medium may comprise, for example and not limitation: magneticstorage media such as a magnetic disk, a hard drive, or removable deviceor magnetic tape; optical storage media such as an optical disc, opticaltape, or machine readable optical encoding; solid state electronicstorage devices such as random access memory (RAM) or read only memory(ROM); or, any other physical device or medium employed to store acomputer program. Computer programs for performing example methods ofdescribed embodiments may also be stored on computer readable storagemedium that is connected to the image processor by way of the Internetor other network or communication medium. Those skilled in the art willfurther readily recognize that the equivalent of such a computer programproduct may also be constructed in hardware.

It should be noted that the term “memory” is equivalent to“computer-accessible memory” in the context of the present disclosure,and can refer to any type of temporary or more enduring data storageworkspace used for storing and operating upon image data and accessibleto a computer system including, for example, a database. The memorycould be non-volatile using, for example, a long-term storage mediumsuch as magnetic or optical storage. Alternately, the memory could be ofa more volatile nature using an electronic circuit such as random-accessmemory (RAM) that is used as a temporary buffer or workspace by amicroprocessor or other control logic processor device. Display data,for example, is typically stored in a temporary storage buffer that canbe directly associated with a display device and is periodicallyrefreshed as needed in order to provide displayed data. This temporarystorage buffer can also be considered to be a memory, as the term isused in the present disclosure. Memory is also used as the dataworkspace for executing and storing intermediate and final results ofcalculations and other processing. Computer-accessible memory can bevolatile, non-volatile, or a hybrid combination of volatile andnon-volatile types.

It should be appreciated and understood that computer program productsfor example embodiments herein may make use of various imagemanipulation algorithms and/or processes that are well known. It shouldbe further appreciated and understood that example computer programproduct embodiments herein may embody algorithms and/or processes notspecifically shown or described herein that are useful forimplementation. Such algorithms and processes may include conventionalutilities that are within the ordinary skill of the image processingarts. Additional aspects of such algorithms and systems, and hardwareand/or software for producing and otherwise processing the images orco-operating with the computer program product of the application, arenot specifically shown or described herein and may be selected from suchalgorithms, systems, hardware, components and elements known in the art.

Example embodiments according to the present disclosure can includevarious features described herein individually or in combination.

While the invention has been illustrated with respect to one or moreimplementations, alterations and/or modifications can be made to theillustrated examples without departing from the spirit and scope of theappended claims. In addition, while a particular feature of theinvention may have been disclosed with respect to only one of severalimplementations/example embodiments, such feature can be combined withone or more other features of the other implementations/exampleembodiments as can be desired and advantageous for any given orparticular function. The term “a” or “at least one of” is used to meanone or more of the listed items can be selected. The term “about”indicates that the value listed can be somewhat altered, as long as thealteration does not result in nonconformance of the process or structureto the illustrated example embodiment. Other embodiments of theinvention may become apparent to those skilled in the art fromconsideration of the specification and practice of the inventiondisclosed herein. It is intended that the specification and examples beconsidered as examples only, with a true scope and spirit of theinvention being indicated by the following claims.

What is claimed is:
 1. A method for intraoral imaging, the method comprising the steps of: (a) generating one or more output imaging signals from an intraoral probe; (b) acquiring multimodal image content from each of a plurality of intraoral surface locations for a patient's dentition according to tissue response from the one or more imaging signals and associating spatial coordinates to the acquired multimodal image content; (c) generating a surface contour of the patient dentition by reconstructing and stitching from a data subset of the acquired multimodal image content, and preserving the association of spatial coordinates of the multimodal image content to the stitched surface contour; (d) generating tooth outlines for one or more teeth from the generated surface contour and arranging the generated outlines as a dental chart representing a spatial ordering of the one or more teeth and of supporting gum tissue adjacent to the teeth; (e) populating the dental chart by analyzing the acquired multimodal image content and indicating analysis results at one or more positions on the dental chart according to the preserved association of spatial coordinates; and (f) displaying the populated dental chart.
 2. The method of claim 1, wherein the step of acquiring multimodal image content comprises directing the first and second output imaging signals along a common imaging path.
 3. The method of claim 1, wherein the method further comprises a step of updating a populated dental chart by: (i) acquiring updated multimodal image content from one or more intraoral surface locations; (ii) reconstructing updated surface views from a data subset of the updated multimodal image content; (iii) stitching the reconstructed updated surface views to the surface contour of the patient dentition; and (iv) mapping the updated multimodal image content to spatial coordinates according to the populated dental chart.
 4. The method of claim 3, wherein the method further comprises a step of highlighting the relative location of the updated multimodal image content on the populated dental chart.
 5. The method of claim 4, wherein the highlighting is color-coded according to the mode of the updated multimodal image content.
 6. The method of claim 1, wherein the method further comprises a step of indicating a relative position of an intraoral scanner with respect to patient dentition on the populated dental chart.
 7. The method of claim 1, wherein displaying indicates a status for acquisition or processing of one or more modes of image content.
 8. The method of claim 1, wherein the step of displaying the populated dental chart further comprises presenting either a flat 2D view or a perspective 3D view in response to an operator instruction.
 9. The method of claim 1, wherein the step of displaying the populated dental chart further comprises displaying partial analysis results for one or more imaging modes in response to an operator instruction.
 10. The method of claim 1, wherein the method further comprises the steps of storing multimodal image content from successive imaging sessions, and rendering successive versions of the stored image content to the display.
 11. The method of claim 1, wherein the method further comprises a step of updating a populated dental chart by: (i) accepting operator instruction entries that specify one or more intraoral surface locations requiring updated multimodal image content; (ii) acquiring the updated multimodal image content from the one or more intraoral surface locations; (iii) mapping the acquired updated image content to spatial coordinates according to the populated dental chart; and (iv) highlighting the relative location of the updated image content on the populated dental chart.
 12. The method of claim 11, wherein the method further comprises a step of providing visual or audible operator feedback on acquisition status.
 13. The method of claim 1, wherein the one or more output imaging signals differ from each other in at least one of wavelength range, wavelength sequence, bandwidth, or coherence.
 14. The method of claim 1, wherein a first output imaging signal comprises color light, from three or more primary colors.
 15. The method of claim 1, wherein a first output imaging signal comprises a swept source laser.
 16. The method of claim 1, wherein the tissue response to the first output imaging signal includes fluorescence.
 17. A method for intraoral imaging, the method comprising the steps of: (a) generating a plurality of output imaging signals from an intraoral probe, wherein the output imaging signals are directed along a common axis and wherein the generated signals differ from each other in at least one of wavelength range, wavelength sequence, bandwidth, or coherence length; (b) acquiring multimodal image content from each of a plurality of intraoral surface locations for a patient's dentition according to tissue response to the plurality of output imaging signals and associating spatial coordinates to the acquired multimodal image content; (c) generating a surface contour of the patient dentition by reconstructing and stitching from a data subset of the acquired multimodal image content, and preserving the association of spatial coordinates of the multimodal image content to the stitched surface contour; (d) generating tooth outlines for one or more teeth from the generated surface contour and arranging the generated outlines as a dental chart representing a spatial ordering of the one or more teeth according to the preserved association of spatial coordinates; (e) populating the dental chart by analyzing the acquired multimodal image content and associating the analysis to positions on the dental chart according to the preserved association of spatial coordinates; and (f) displaying the populated dental chart.
 18. The method of claim 17, wherein the step of displaying the populated dental chart comprises displaying a spatial coordinate for an intraoral feature.
 19. The method of claim 17, wherein the plurality of output imaging signals comprises a coherent laser beam.
 20. The method of claim 19, wherein the coherent laser beam repeatedly changes in wavelength.
 21. The method of claim 17, wherein the plurality of output imaging signals comprises an ultrasound signal.
 22. The method of claim 17, wherein the step of populating the dental chart comprises associating image content of two or more different imaging modes to a tooth on the dental chart.
 23. A method for intraoral imaging, the method comprising the steps of: (a) obtaining multimodal image content at each of a plurality of intraoral surface locations from an intraoral probe that is configured to sequentially: (i) direct polychromatic visible illumination to the surface location and acquire surface image content associated with the surface location from reflected polychromatic light; and (ii) direct a surface contour imaging signal to the surface location; (b) reconstructing a surface contour of the patient dentition from the obtained multimodal image content, wherein the reconstruction preserves the spatial association of the acquired surface image content and the reconstructed surface contour; (c) generating tooth outlines for one or more teeth from the reconstruction and arranging the generated outlines as a dental chart representing a spatial ordering of the one or more teeth and of supporting gum tissue adjacent to the teeth; (d) analyzing the acquired image content; (e) populating the dental chart by associating analysis results to positions on the dental chart; and (f) displaying the populated dental chart.
 24. The method of claim 23, wherein the step of populating the dental chart comprises highlighting one or more portions of the analysis results.
 25. The method of claim 24, wherein the acquired surface image content includes a color image.
 26. The method of claim 23, wherein the step of populating the dental chart comprises highlighting the tooth outline using color or shading according to the analysis results.
 27. The method of claim 23, wherein the method further comprises a step of storing, transmitting, or communicating the populated dental chart.
 28. The method of claim 23, wherein the method further comprises the steps of directing an excitation illumination of an excitation wavelength range to the surface location, and acquiring fluorescent light image content associated with the surface location, wherein fluorescent wavelengths of the acquired fluorescent light image content lie outside the excitation wavelength range, and wherein the step of reconstructing further preserves the spatial association of the acquired surface image content with the fluorescent light image content and the reconstructed surface contour.
 29. The method of claim 28, wherein the excitation illumination is provided from a light source that is also used for the polychromatic illumination.
 30. The method of claim 23, wherein the surface contour imaging signal acquires depth-resolved image content.
 31. A method for intraoral imaging, the method comprising the steps of: (a) obtaining multimodal image content at each of a plurality of surface locations within a patient's mouth from an intraoral probe that is configured to sequentially: (i) direct polychromatic visible illumination to the surface location and acquire 2D image content associated with the surface location from reflected polychromatic light; and (ii) direct a point-by-point scan sequence of coherent light beams that penetrate points along the surface location, modulating the wavelength of the scanned coherent light beams at each penetrated point over a wavelength range, to acquire an interference signal having depth-resolved image content; wherein the polychromatic visible illumination and sequence of coherent light beams are directed along a common optical axis of the intraoral probe; (b) reconstructing a surface contour of the patient dentition from the obtained multimodal image content, wherein the reconstruction preserves the association of the acquired 2D image content and depth-resolved image content with each surface location; (c) generating tooth outlines for one or more teeth from the reconstruction and arranging the generated outlines as a dental chart representing a spatial ordering of the one or more teeth and of supporting gum tissue adjacent to the teeth; (d) analyzing the acquired image content and populating the dental chart by associating analysis results to positions on the dental chart; and (e) displaying the populated dental chart.
 32. An intraoral probe, comprising: (a) signal generation circuitry energizable to generate one or more output imaging signals; (b) one or more imaging sensors capable of generating multimodal image content from each of a plurality of intraoral surface locations for a patient's dentition according to detected tissue response to the one or more generated imaging signals; (c) a control logic processor in signal communication with the signal generation circuitry and with the one or more sensors and configured with programmed instructions to: (i) associate spatial coordinates corresponding to the intraoral surface locations with the acquired multimodal image content; (ii) generate a surface contour of the patient dentition by reconstructing and stitching from a data subset of the acquired multimodal image content while preserving the association of spatial coordinates of the multimodal image content to the stitched surface contour; (iii) generate tooth outlines for one or more teeth from the generated surface contour; (iv) arrange the generated outlines as a dental chart representing a spatial ordering of the one or more teeth and of supporting gum tissue adjacent to the teeth; (v) populate the dental chart by analyzing the acquired multimodal image content and by associating the analysis to positions on the dental chart according to the preserved association of spatial coordinates; and (d) a display in signal communication with the control logic processor for displaying the populated dental chart. 